1,3-butadiene is a major product of the petrochemical industry. Its simple chemical structure combined with its low molecular weight and high chemical reactivity makes it a very useful building block in the synthesis of other materials. 1,3-butadiene can be used as a monomer starting material for preparation of various polymers, including synthetic rubbers. 1,3-butadiene can also be used as a feedstock in the production of adiponitrile or as a substrate in certain Diels-Alder reactions.
1,3-butadiene can be obtained from different sources, including dehydrogenation of n-butane and the reaction of ethanol. 1,3-butadiene can also be isolated from C4 hydrocarbon streams, e.g., C4 fractions obtained from the steam cracking of naphtha, gas (e.g., ethane, propane, butane and liquid petroleum gas (LPG)) cracking, the catalytic cracking of gas oil and/or vacuum gas oil, the catalytic dehydrogenation of butane and butene, and the oxidative dehydrogenation of butene. C4 hydrocarbons streams can include C4 alkanes, e.g., butane, isobutane; C4 alkenes, e.g., isobutene, 1-butene, trans-2-butene, cis-2-butene; C4 alkadienes, e.g., 1,3-butadiene, 1,2-butadiene, and/or C4 alkynes, e.g., vinylacetylene, ethylacetylene, dimethylacetylene. In some embodiments, the C4 hydrocarbon streams can also include a C3 alkyne such as methylacetylene. Due to the low differences in the relative volatilities of such compounds, the isolation of crude 1,3-butadiene from a C4 fraction can be complicated and is generally carried out by extractive distillation.
Certain methods and systems for purifying 1,3-butadiene are known in the art. U.S. Pat. No. 7,556,717 discloses methods for extractive distillation using a divided wall distillation column, where a stream containing 1,3-butadiene and solvent can be obtained from the common bottom region of the column. Japanese Patent No. JPH1057704 describes the use of a divided wall distillation column for the separation of a multicomponent feedstream. U.S. Pat. No. 7,462,277 discloses methods and systems for extractive distillation of a C4 hydrocarbon stream that includes the use of a divided wall distillation column to remove butanes from the top of the first region, butenes are removed from the top of the second region and 1,3-butadiene is removed from the combined bottom region of the column. U.S. Pat. No. 7,528,290 discloses the use of a divided wall distillation column for the separation of 1-butene from a mixed C4 hydrocarbon stream. U.S. Pat. No. 7,619,126 discloses methods and systems for the distillation of 1,3-butadiene from a C4 hydrocarbon stream, which includes the use of a divided wall distillation column that is coupled to an extractive scrubbing column. U.S. Pat. No. 7,692,053 disclose methods and systems for the distillation of 1,3-butadiene from a C4 hydrocarbon stream, that include the use of a divided wall column that is coupled to an extractive wash column and/or an acetylenes outgasser column.
There remains a need in the art for methods and systems for producing 1,3-butadiene.